Add --with-innobase-db to configure.


acconfig.h:
  HAVE_INNOBASE_DB
acinclude.m4:
  add MYSQL_CHECK_INNOBASE
configure.in:
  use MYSQL_CHECK_INNOBASE and configure innobase directory
innobase/configure.in:
  add AM_MAINTAINER_MODE
innobase/include/lock0types.h:
  define lock_t
innobase/include/os0file.h:
  define S_IRWX[UGO] if needed
innobase/include/os0sync.h:
  use pthread_cond_t instead of mutex
innobase/include/sync0types.h:
  define mutex_t
innobase/os/os0sync.c:
  use pthread_cond_t instead of mutex
sql/Makefile.am:
  add @innobase_{includes,libs}@
sql/ha_innobase.cc:
  fix casts